This invention relates to machines and methods for successively feeding stacked blanks.
Today there exists many industrial machines and processes which require successive feedings of blanks and sheet material. For example, box and carton erecting and packaging machines typically require a continuous supply of cardboard blanks to be fed thereto for box erection and packaging. Similarly, there exists many machines for forming metallic articles from flat blanks which similarly require a continuous supply of blanks fed thereto.
For most modern day machines and process lines, a manual, consecutive feeding of blanks is entirely too slow to accommodate the available speed of the machines and lines. To enhance the speed of supply the blanks have been piled one upon the other in stacks from which they are automatically extracted one at a time for feeding to the machine. As exemplified by that machine disclosed in U.S. Pat. No. 907,944 these blank feeding machines have previously comprised suction cups adapted to engage and lift the outermost blank from a blank stack and then position it upon a conveyor for transportation to an adjacent machine which performs operations thereon. More recently, in an effort to increase further speed of operations, other machines, such as that disclosed in U.S. Pat. No. 3,016,240, have been developed having gates effective in continuously moving in an advanced direction the blanks from their stacks to conveyors and into engagement with feed rollers mounted adjacent thereto.
Though the prior art automatic feeding machines have provided a decisive advantage over manual operations in successively feeding blanks and sheet materials, certain problems have nevertheless persisted. For example, advances in the machines to which the blanks are fed are continually creating demands for greater and greater speeds of blank injections. Such increases in speeds have been made only with a lessening in reliability. Recent attempts to increase speeds have thus been accomplished only at a sacrifice in the precision of spacings made between adjacent blanks upon the conveyor belts transporting them from their storage stacks to the operative machine. All too often actual jamming has occurred as has simultaneous doubling and even occasional triplings of blank removals and feedings. This has particularly been a troublesome point with the very recent development of machines having feed rollers which operate adjacent inclined hoppers or chutes in which stacks of blanks are stored at an incline and which extract them directly from the hopper one at a time.
Accordingly, it is a general object of the present invention to provide improved machines and methods for successively feeding stacked blanks and sheet materials.
More specifically, it is an object of the present invention to provide machines and methods for successively feeding stacked blanks with greater speed and precision of blank spacings.
Another object of the invention is to provide machines and methods of the type described having improved reliability.
Yet another object of the invention is to provide machines and methods of the type described of relatively simple and economic construction and which are adapted for use with existing devices for extracting blanks from stacks.